Strap feed device

ABSTRACT

A strap tensioning means in a strapping machine employing a rotary feed wheel and an idler wheel between which strap is fed. The periphery of one of the wheels is covered with a resilient high friction surface for minimizing strap slippage and the two wheels are geared together to eliminate relative rotation of one wheel to the other.

United States Patent [56] References Cited UNITED STATES PATENTS 7/1964 Halletal.............r..vmlr

[72] Inventor Robert F. Plattner 3,139,813 100/30 X 3,272.]13 9/1966 Otto 100/32 X Primary Examinerwilliam i. Price Attorney-William P. Porcelli Chicago Heights. III.

121 1 Appl. No. 884,216

[22] Filed Dec. 11, 1969 [45] Patented July 6,1971

[73] Assignee lnterlake Steel Corporation Chicago, Ill.

[54] STRAP FEED DEVICE 7 Claims, 3 Drawing Figs.

ABSTRACT: A strap tensioning means in a strapping machine n mls y 0 nw 60 4 mm m" 2" .2m Tm m m MS I I n W .m R U .mF .A N 5 55 n o m Ur. wd e me h h m w 2. e m h t m f r o m e n g 0 f 0 W employing a rotary feed wheel and an idler wheel b which strap is fed. The periphe covered with a resilient high friction surface for minim strap slippage and the two wheels are 30 eliminate relative rotation of one wheei to the other.

PATENTED JUL BISTI 3,590,728

SHEET 1 OF 2 f7ZZ/6IZZOP ffa ari FP/QZ ZIZGW B J W (M F Q7 QM PATENTEUJHL 6l97l sum 2 or 2 IIIIII lllllllllll 111 1111111 STRAP FEED DEVICE BACKGROUND AND SUMMARY OF THE INVENTION This invention relates to the art of strapping machines and particularly to an improved strapping machine for binding by encircling an object, package, box or other bundle, with a loop of strap having its supply and leading strap ends overlapping each other and joined together by means of ajoint formed by interlocking the strap ends with an encircling tubular metal seal or other means.

The invention more specifically relates to a strapping machine having improved strap feeding means for both feeding a length of strap into a loop around the object to be bound and, thereafter, for withdrawing the strap in the opposite direction for shrinking the strap loop onto the object and tensioning it into a tight loop on the object.

In strapping machines of the general type referred to, some have a strap feed wheel or pinion which is urged toward an idler wheel between which the strap is fed as the feed wheel or pinion is driven with a rotary motion. In such an arrangement, the idler wheel acts as a backing to cause gripping of the strap for feeding purposes as the feed wheel pinion is rotated. With such a strap feed mechanism, there is nothing but the friction of the contacting portions of the feed wheel and the idler wheel bearing against the strap being fed therebetween to prevent slippage. When the feed mechanism drives against the strap in which the tension has increased significantly, slippage may occur. When using metal strap as the binding material, a certain amount of slippage is permissible. The harm is perhaps a scratching of the metal surface of the strap. However, when a plastic strap or strap made of other softer materials is employed, excessive slippage of the strap against the surface of the feed wheel or pinion can result in cutting or breaking through the relatively soft strap. This is possible when the feed wheel pinion has an outside periphery of sharp teeth which are employed to bite into the strap for feeding.

To minimize a slippage condition between the strap and the mating feed means, it is an object of this invention to coat or otherwise wrap the periphery of the idler wheel with a coating of rubber or like material which has a high coefficient of friction and which is resilient so that the strap being fed is urged into a continually formed depression in it as the strap feed occurs which increases the area of grip between the strap and the idler wheel.

Even with a rubber coated idler wheel, some slippage may occur of the feed wheelteeth across the strap, although the strap may not necessarily slip across the rubber surface of the idler wheel. When this occurs, the scraping of the feed wheel teeth over the strap may still cut through the strap. If so, the teeth then mutilate the rubber coating on the idler wheel to damage it. With excessive treatment of this sort, the idler wheel would necessarily have to be replaced frequently. In order to overcome this problem, it is an important object of this invention to provide gearing means between the feed wheel and the idler wheel so that there can be no material rotation of the feed wheel relative to the idler wheel. This entirely eliminates scraping of the feed wheel teeth across the strap surface so long as the rubber coating on the idler wheel does not permit any slippage of the strap relative to the idler wheel.

Other objects and advantages of the invention can be better understood by referring to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a perspective view ofa portion ofa roller support type conveyor line provided with a strapping machine embodying the invention;

FIG. 2 is a partially cutaway view of a preferred embodiment of strap feed means employing the invention; and

H6. 3 is a sectional view, partially cutaway as viewed along the line 3-3 of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT As shown in FIG. I, the strapping machine or head 1 embodying the invention is shown positioned between two roller conveyor lengths 2 and 3. The head 1 is shrouded with a cover 4 for better appearance and to protect the operator from accidental injury because of otherwise exposed moving parts. The roller conveyor lengths 2 and 3 are suitably supported with leg supports 5, 6 and 7, as required, and the strapping head 1 is suitably supported on a pipe frame 8. In front of the head and extending below the upper level of the conveyor lengths 2 and 3 is a channel-shaped strap guide 9 for suitably guiding a loop of strap 10 around a package 11 being strapped and insuring that the leading end of the strap loop is properly fed under the package ill and up into proper location with the working parts of the strapping head 1. It should be observed that the front strapping region la of the strapping head extends vertically in the particular arrangement shown, but the head can be oriented to any angle so that the front strapping region Ia can extend in any direction, including facing either upward, downward or sideways at any angle. The arrangement shown in FIG. 1 is intended for purposes of of example only.

The head shown can be substantially of the structure shown in US. Pat. No. 3, l39,8l3, issued July 7, 1964, to M. B. Hall, et al., except as modified herein to include the features of this invention.

The strap head 1 is provided with a single large rectangular plate 12 which is the main support frame of the components of the strapping head 1. The major operating portions of their type of head 1 consist of the strap feed and the slack takeup and tensioning portions which embody the features of this invention, strap gripping portions, strap shear means, a means for joining the strap ends of the strap loop together to form a joint and other related components, such as a storage and feeding means for metal seals which are employed to form the strap joints. All of these features are shown and explained in detail in the above mentioned US. Pat. No. 3,139,8l3.

The strap feed, slack takeup and tensioning portion 13 is indicated generally in FIG. 1 and in detail in FIGS. 2 and 3. It consists of a serrated rotary feed wheel 20 which is secured to the end of a shaft 21. The shaft 21 is the drive shaft of an air motor 22 provided with suitable means for securing it to the main frame 12. The air motor 20 is mounted on one side of the frame 12 and projects through a circular hole 25 to the other side of the frame 12. The rotary feed wheel 20 is positioned so that the teeth or serration 26 about its periphery extend parallel to an annular wall 27 on a strap feed idler wheel 28 adjacent to it. The idler wheel 28 is considerably larger in diameter than the rotary feed wheel and it is mounted on a bearing 30 to the outer end ofa shaft 29. As an idler, it is free to rotate on the bearing 30 relative to the shaft: 29. The shaft 29, in turn, is secured at its inner end to a flange 31 which is secured to one end of a larger shaft 32. Shaft 29 is mounted on the flange 31 with its center eccentric with the center of the shaft 32. The shaft 32 is freely joumaled on bearings in a housing suitably secured to the plate 12. With this arrangement, the shaft 29 is subject to eccentric movement on the shaft 32 and this, in turn, allows eccentric movement of the idler wheel 28 relative to the shaft 32 and in addition to concentric rotation of the idler wheel 28 on its supporting shaft 29.

The idler wheel 28 is provided with an annular ring 36 of rubber or other materials having a relatively high coefficient of friction and preferably resilient. The ring 36 can be a single loop stretched over the idler wheel 28 or it can be applied as a coating. Furthermore, it can be in the form of a slightly roughened surface or it can be a coating impregnated with particles which produce a surface having a high coefficient of friction. Other materials, such as polyurethane can be employed. The advantage of polyurethane is its ability to withstand abuse.

Attached to the outside face 28a of the idler wheel 28 is a gear 37 which is suitably secured thereto by means of four bolt-type fasteners 38 so that the gear is mounted concentrically with the center of the shaft 29. Attached to the outside surface of the rotary feed wheel 20 is a pinion gear 39 which is suitably keyed in a fixed position on the shaft 21 by means ofa key 40 so that rotation of the shaft 21 causes identical rotation of the rotaryfeed wheel 20 together with the pinion gear.39, the pinion gear 39 having teeth 39a which mesh with teeth 37b of the gear 37. In this manner, upon rotation of the rotary feed wheel 20, the pinion 39 rotates with the gear 37 and the idler wheel 38 without difference in angular speed or difference in the linear velocity of the idler wheel 28 and the rotary feed wheel 20 in the region 41 where they come together during rotation.

The strap supplied in the direction of the arrow 42 is guided and fed between the teeth of the rotary feed wheel 20 and the outer surface 36a of the ring 36 which is the periphery of the idler wheel 28. The strap is then encircled around the idler wheel 28 and it emerges to become part of a strap loop encircled about an object to be strapped. This strap feed motion occurs when the rotary wheel 20 is rotated clockwise and the idler wheel 28 is thereby rotated counterclockwise as viewed in H6. 2.

When slack is to be removed from the strap loop 10 and the strap tensioned, the rotary feed wheel 20 is rotated counterclockwise which causes the idler wheel 28 to be rotated clockwise.

During the tensioning portion of the strap, relatively high tensions are developed in the strap with a tendency for the strap to slip between the gripping portions of the rotary feed wheel 20 and the idler wheel28. With the ring 36 on the idler wheel 28, the strap is prevented from slipping relative to the idler wheel 28. With no slippage of the strap occurring on the surface 36a of the ring 36, there is no slippage of the strap relative to the rotary feed wheel 20 because the idler wheel 28 is geared to the rotary feed wheel 20 which prevents relative peripheral movement of the idler wheel 28 and the rotary feed wheel 20. With this arrangement, assuming no slippage of the strap occurs over the ring surface 36a, there is no scraping or cutting into the strap surface by the serrations or teeth 26 of the rotary feed wheel 20. The result is that the teeth 26 do not damage the strap and do not cut through it. Therefore, with strap in place, this also avoids contact of the teeth 26 with the ring 36 and thereby minimizes damage to the ring 36 which would necessitate early replacement of the ring 36.

Although the apparatus shown can be employed with strap made of metal it is very advantageous for use with plastic strap which, by comparison to metal, is soft with a tendency to cut through it easier by the action of the teeth 26 on the rotary feed wheel 20.

Another advantage of the ring 36 when it is made .of resilient material is the additional wrap of the strap in the region 41 around the rotary feed wheel 20 mating with a depression in the resilient ring 36 due to the strap gripping pressure. This increases the area of contact and thereby further assists in minimizing any tendency of the strap to slip over the ring surface 36a.

As explained in the US. Pat. No. 3, l 39,8 1 3, referred to, the eccentric movement of the idler wheel 28, because of the eecentric mounting of the shaft 29 relative to the shaft 32, permits the idler wheel 28 to be shifted into close contact with the rotary feed wheel 20 for the strap engaging position.

Although only a single embodiment of the invention has been shown and described, it should be clearly understood that the invention can be made in different ways without departing from the true scope of the invention as defined in the appended claim.

lclaim:

l. The combination in a strapping machine comprising, strap tensioning means for tensioning a length of strap encircled in a strap loop about an object, said strap tensioning means having a rotary feed wheel and an idler wheel between which the strap passes while being tensioned, said rotary feed wheel supported on a shaft driven by a power means for tensioning, said idler wheel mounted on an adjacent shaft which is aligned relative to the rotary feed wheel so that the rotary feed wheel and the idler wheel can be urged toward each other to grip the strap passed therebetween, said rotary feed wheel and idler wheel having outside peripheral surfaces of a high coefficient of friction to minimize slippage of the'wheels relative to the strap passing between them, said rotary feed wheel and said idler wheel being geared together so that rotation of one follows rotation of the other.

2. The combination in a strapping machine defined by claim 1 characterized by at least one of said peripheral surfaces being rubber.

3. The combination in a strapping machine defined by claim 1 characterized by, at least one of said peripheral surfaces being of a resilient material which deforms to the contour of the periphery of the wheel bearing against it as the rotary feed wheel and the idler wheel grip the strap.

4. The combination in a strapping machine comprising, strap tensioning means for tensioning a length of strap encircled in a strap loop about an object, said strap tensioning means having a rotary feed wheel and an idler wheel between which the strap passes while being tensioned, said rotary feed wheel supported on a shaft driven by a power means for tensioning, said idler wheel mounted on an adjacent shaft which is aligned relative to the rotary feed wheel so that the rotary feed wheel and the idler wheel can be urged toward each other to grip the strap passed therebetween, said rotary feed wheel and said idler wheel being geared together so that rotation of one follows rotation of the other.

5. The combination in a strapping machine defined by claim 1 characterized by a first gear mounted on one face of the idler wheel and a second gear mounted on one face of the rotary feed wheel, said gears having teeth on their peripheries meshing with each other to provide the geared together relationship which causes the rotation of one wheel to follow the rotation of the other.

6. The combination in a strapping machine defined by claim 1 characterized by, at least one of said peripheral surfaces being polyurethane.

7. The combination in a strapping machine defined by claim 1 characterized by, at least one of said peripheral surfaces being an adherent coating impregnated with particles which produce a surface having a high coefficient of friction. 

1. The combination in a strapping machine comprising, strap tensioning means for tensioning a length of strap encircled in a strap loop about an object, said strap tensioning means having a rotary feed wheel and an idler wheel between which the strap passes while being tensioned, said rotary feed wheel supported on a shaft driven by a power means for tensioning, said idler wheel mounted on an adjacent shaft which is aligned relative to the rotary feed wheel so that the rotary feed wheel and the idler wheel can be urged toward each other to grip the strap passed therebetween, said rotary feed wheel and idler wheel having outside peripheral surfaces of a high coefficient of friction to minimize slippage of the wheels relative to the strap passing between them, said rotary feed wheel and said idler wheel being geared together so that rotation of one follows rotation of the other.
 2. The combination in a strapping machine defined by claim 1 characterized by at least one of said peripheral surfaces being rubber.
 3. The combination in a strapping machine defined by claim 1 characterized by, at least one of said peripheral surfaces being of a resilient material which deforms to the contour of the periphery of the wheel bearing against it as the rotary feed wheel and the idler wheel grip the strap.
 4. The combination in a strapping machine comprising, strap tensioning means for tensioning a length of strap encircled in a strap loop about an object, said strap tensioning means having a rotary feed wheel and an idler wheel between which the strap passes while being tensioned, said rotary feed wheel supported on a shaft driven by a power means for tensioning, said idler wheel mounted on an adjacent shaft which is aligned relative to the rotary feed wheel so that the rotary feed wheel and the idler wheel can be urged toward each other to grip the strap passed therebetween, said rotary feed wheel and said idler wheel being geared together so that rotation of one follows rotation of the other.
 5. The combination in a strapping machine defined by claim 1 characterized by a first gear mounted on one face of the idler wheel and a second gear mounted on one face of the rotary feed wheel, said gears having teeth on their peripheries meshing with each other to provide the geared together relationship which causes the rotation of one wheel to follow the rotation of the other.
 6. The combination in a strapping machine defined by claim 1 characterized by, at least one of said peripheral surfaces being polyurethane.
 7. The combination in a strapping machine defined by claim 1 characterized by, at least one of said peripheral surfaces being an adherent coating impregnated with particles which produce a surface having a high coefficient of friction. 